1. Field of the Invention
The present invention relates to a biometrics system and biometrics method utilizing characteristics of a portion of the human body to perform individual authentication, and in particular relates to a biometrics system and biometrics method which guide a body part into a state of registration when detecting biometrics information for use in verification against registered biometrics information.
2. Description of the Related Art
There exist numerous portions of the human body, such as fingerprints and toeprints, the retinas of the eyes, facial features, and blood vessels, which can be used to discriminate individuals. Advances in biometrics technology in recent years have been accompanied by the appearance of various devices to recognize the characteristics of such portions of human bodies and perform individual authentication.
Methods of individual authentication through biometrics have been provided which utilize facial features, the iris of the eye, blood vessels in the palm and fingers, finger prints and palm-prints, and similar. These methods have been used in various fields as individual authentication methods affording a high level of security.
For example, comparatively large amounts of individual characteristic information are obtained from blood vessels in the palm and back of the hand, and blood vessel (vein) patterns remain unchanged throughout life from infancy and are regarded as being completely unique, and so are well-suited to individual authentication. Such individual authentication methods are here explained. At the time of registration or of authentication the user brings his palm into proximity with an image capture device. The image capture device emits near-infrared rays, which are incident on the palm of the hand. The image capture device uses a sensor to capture near-infrared rays rebounding from the palm of the hand.
Hemoglobin in the red corpuscles flowing in the veins has lost oxygen. This hemoglobin (reduced hemoglobin) absorbs near-infrared rays. Consequently when near-infrared rays are made incident on the palm of a hand, reflection is reduced only in the areas in which there are veins, and the intensity of the reflected near-infrared rays can be used to identify the positions of veins.
At the time of biometrics registration, a user first utilizes an image capture device to register vein image data for the palm of his own hand on a server and on a card. Then, in order to perform individual authentication, the user utilizes an image capture device to cause reading of vein image data for his own palm. The registered vein image retrieved using the user's ID is verified against the vein pattern of the vein verification image thus read to perform individual authentication (see for example Japanese Patent Laid-open No. 2004-062826).
In such biometrics information detection, the body part can be moved freely with respect to the image capture device, and in particular, the hand, face, and fingers can be moved freely. On the other hand, it is necessary for precise verification that the body part for detection be positioned within the range of image capture of the image capture device. As such a method, a method for detecting, at the time of authentication, the position and orientation of the hand upon each image capture, and using a display or voice output to notify the user that the hand position or orientation is inappropriate (see for example WO 04/021884), and a method of displaying a hand shape or other standard shape-pattern, and for guiding the user in the mode of image capture, have been proposed (see for example WO 04/021884 (FIG. 3) and Japanese Patent Laid-open No. 2001-273948).
Methods which include the shape of the hand in verification based on blood vessel images have also been proposed. That is, methods have been proposed in which, at the time of registration the shape of the hand is also registered in advance, and at the time of verification a judgment is made as to whether the shape of the hand for which an image is captured is similar to the shape of the hand at the time of registration, and if the degree of similarity is low, blood vessel image verification is not performed, but if the degree of similarity is high, blood vessel image verification is performed (see for example WO04/021884).
In the former technology of the prior art, a standard shape is displayed, and the user is guided to an appropriate image capture mode; or, an image of detection of the body part is used in analysis to determine whether the detected body part is in the appropriate image capture range, and guidance is provided. However, when such guidance is performed, if the circumstances of body part detection at the time of registration differ from the circumstances of body part image capture at the time of authentication despite this guidance into the image capture range, satisfactory verification results cannot be obtained.
Examples in which the circumstances of image capture of a body part are different during registration and during authentication include, for example, in the case of authentication using the palm of the hand, a degree of difference in the spreading of the fingers at the time of registration and at the time of authentication; and in the case of authentication using facial features, different orientations of the face, or the presence and absence of glasses, at the time of registration and at the time of authentication. Thus even when the position and orientation of the hand or face are similar, often the verification results fail to match.
In the latter technology of the prior art, the shape of a hand is used together with an authentication algorithm, so that when there is authentication failure, the user does not directly understand the cause, and often it is not possible to determine how the body part should be guided with respect to the image capture device. In particular, persons with little experience with the device, and elderly and other persons, will tend to experience inconvenience.
In general, the user does not remember the state of image capture of the body part at the time of registration, and moreover the user will have a strong aversion to being forced into a strictly defined state (position or similar) of the body part for image capture at the time of registration. Consequently from the standpoint of the device manufacturer, because there are cases in which unanticipated events occur and verification errors may arise, it is expected that in such cases, if the user, if the individual in question, will lose confidence in such biometrics authentication. Particularly when used in automated equipment (automated cash transaction machines, automated vending machines, in entrance doors to dwellings, and similar), because dedicated personnel are not on site, trouble is incurred in determining the cause of the problem, giving rise to a further loss of confidence in biometrics authentication.